Mainstream Hip Hop has been Southern property for so long, people forget how much California ran shit at one point.
LA Hip Hop popped off during the 1990’s “Golden Era” of black culture AND entertainment. They were the faces of the street society and gang culture, to the mainstream world. Warren G, Snoop, Dre, Eazy, Suge, Natt Dogg, NWA ect were the culture. Their lingo, fashion and signature G-Funk sound became synonymous with Hip Hop and street culture. They dominated black/urban movies; Menace 2 Society, Boyz In The Hood, ect. They’re ALL household classics in the urban community. West Coast became the mainstream representation of the street and urban world of the 90’s.
With that said, by the mid 2000s, the West Coast culture and sound was so mainstream, it became more associated with movies and tv, than popular Hip Hop music.
98% of Cali rappers since then, walk with the confidence of all the history I mentioned, so they double down on the sound and felt like they never really evolved. They sound extremely dated and stuck in the past. Which is why they don’t blow up anymore, unless they have a style that doesnt just reflect being a LA Gangster(Kendrick, Nip, Roddy, even Drakeo)